1. Field of the Invention
The present invention relates to an electronic flash device and to an image pickup apparatus provided with this electronic flash device.
2. Description of the Related Art
In recent years, a compact electronic flash unit is required in response to a demand for downsizing an image pickup apparatus such as a digital camera. A flash unit mounted on a digital camera is provided with a trigger coil for emitting a xenon tube. Since the trigger coil generates a high voltage, it is necessary to keep a sufficient creepage distance between the trigger coil and a conductive element, when arranging the conductive element near the trigger coil. However, when the sufficient creepage distance is kept by increasing an air clearance, there is a problem of increasing the size of the flash unit. Therefore, in order to solve this problem, a technique that secures the creepage distance by covering the trigger coil, which is mounted on a flash substrate constituting the flash unit, by an insulation cap formed of an insulating member is proposed (for example, see Japanese Laid-Open Patent Publication (Kokai) No. 2006-98980 (JP 2006-98980A)).
In recent years, a liquid crystal display section arranged in a camera back becomes wider in a horizontal direction, which requires a product of which a height in a vertical direction is suppressed. In a conventional digital camera of which the flash emission section (referred to as an “emission section”) is fixed, there is no space to arrange elements other than a main capacitor under the emission section on which an emission circuit is arranged. On the other hand, in a case where the emission section moves up and down with respect to a camera body (what is called a pop-up flash), a metallic frame for moving the trigger coil has to be arranged behind the emission section closely in order to downsize the emission section. Therefore, a trigger coil of surface mounting type of which a secondary electrode section is contained on a circuit board is used so that the circuit board on which the trigger coil is mounted is miniaturized.
However, when the secondary electrode section of the trigger coil as a high voltage section is contained on the circuit board, the covering of the trigger coil by the insulation cap as disclosed in the above-mentioned publication is insufficient to keep the creepage distance in the downsized electronic flash device. Therefore, an electric leak may occur from the secondary electrode section or the circuit board pattern that is electrically connected with the secondary electrode section to conductive materials such as a surrounding metal exterior and a metallic frame.